1. Field of the Invention
The present invention relates to an arrangement of a pluggable optical transceiver able to be closely set within a joined cage of the host system.
2. Related Prior Art
A pluggable optical transceiver, that provides a light-transmitting device and a light-receiving device, transmits or receives optical signals through an optical connector. A pluggable transceiver typically comprises an optical receptacle that receives the optical connector and a body that encloses the light-transmitting device, the light-receiving device, electronic components, a circuit board, and so on. Such a pluggable transceiver is set within a metal cage provided in the host system to communicate with the host system.
The pluggable transceiver in the metal cover thereof usually comes in electrically contact with the metal cage and the front panel of the host system to suppress the electromagnetic interference (EMI) radiation and to enhance the heat dissipation from the transceiver to the host system. The U.S. Pat. No. 6,335,869, has disclosed an optical transceiver with a metal cover. This metal cover provides in the front end portion thereof a finger elastically protruding outwardly and, when the transceiver is set within the cage, this finger comes in contact with the edge of the opening of the face panel, through which the transceiver is set, to enhance the shielding function.
The Japanese Patent Application, published as JP-2007-233261A, has disclosed another technique to enhance the shielding function, in which the elastic finger provided in the metal cover of the transceiver protrudes from the metal cover to come in contact with the cage when the optical receptacle of the transceiver receives the optical connector to secure the smooth extraction of the transceiver from the cage. The U.S. Pat. No. 6,724,641 and U.S. Pat. No. 6,824,429, have disclosed a system where a plurality of pluggable transceivers are set within a joined cage.
FIG. 7 exemplarily illustrates a conventional pluggable transceiver 1 that comprises an optical receptacle 2 in a front side to receive the optical connector, a body subsequent to the optical receptacle 2 and a metal cover 3 enclosing the body. The cover 3 provides a plurality of top fingers 4 in the front end close to the optical receptacle, and another fingers, 5a and 5b, in respective sides, 3a and 3b. When the transceiver 1 is set within the cage, these top fingers 4 and side fingers, 5a and 5b, come in contact with an inner surface of the metal cage to secure the electrical contact therebetween not only to stabilize the ground potential but to enhance the EMI shielding function.
In order to enhance the EMI shielding function of the electronic equipment; the gap exposing the inside of the equipment should be narrow as possible. This mechanism commonly applicable for a case when a single transceiver is set within a single cage and for a case where a plurality of transceivers is set within a cage with partition walls between the set transceivers. Individual transceiver comes in electrically contact with the cage and the partition wall by the fingers protruding from the transceiver, such as those disclosed in U.S. Pat. No. 6,724,641.
Continuous request has arisen to make the electronic equipment compact and less power consumption. The host system for the optical communication is also necessary to downsize without degrading the EMI shielding function. The conventional arrangement, where the single cage is for the single transceiver, seems to have a limitation for the downsizing of the system.
Moreover, recent optical communication further increases the transmission speed thereof not only the increase of the mass of data to be transmitted. A relatively broader opening in the face panel of the host system, that is, the face panel shows a slightly wider gap with respect to the transceiver, may suppress the EMI radiation through the opening. However, a slight gap of the front panel may leak the EMI radiation in high frequencies. Accordingly, the host system and the pluggable transceiver are necessary to have the configuration where the gap between the transceiver and the opening of the front panel is small as possible, even when the multiple transceivers are set within the single cage without any center partition between the set transceivers.